This invention is broadly concerned with a sack for packing powdered materials therein, and is particularly concerned with a sack with a sealing member by which the sack is sealed off containing the powdered materials therein.
This invention is also directed to a method and an apparatus for packing powdered materials into a sack.
One conventional method for packing powder materials into a sack and for sealing off the sack containing the powdered materials involves supplying powdered materials into a sack through a supply pipe inserted into a sealing member of the sack, and thereafter jetting an appropriate dose of an adhesive agent from slits or fine holes, arranged on the cylindrical surface of the supply pipe, to the inner surface of the sealing member mounted at a predetemined position of the sack. In this manner, adhesive is applied to the sealing member, so that the sack containing the supplied powdered materials therein can be sealed off because the sealing member is pressed outward by the powdered materials contained in the sack when the sack is released from the supply pipe.
In such a prior method, however, there have been various problems. For example, the slits or fine holes arranged on the cylindrical surface of the supply pipe, which tend to be damped by an adhesive agent, may be inconveniently bunged because of the agglutination of powdered materials when the supply pipe is released from the sack. Moreover, it is difficult to clean the bunged slits or holes particularly when the packing operation is restarted after a long discontinuance. Thus it is necessary to clean manually the bunged slits or holes every time the packing operation is to be restarted, which is very troublesome and inefficient for an operator.
On the other hand, different problems are caused in the sack itself. The continuous packing operation tends to cause the outer cylindrical surface of the supply pipe to grow sticky on account of the adhesive agent when the packing operation is continuously performed. If this sticky condition of the pipe is or grows severe enough, the sealing member is torn off by the adhesion of the pipe when the sack is released from the pipe.